Steel is used in small arms cases and projectiles during wartime shortages of strategic materials like copper, zince, tin, etc. Many countries continue their wartime production of steel jacketed ammo for cost and scarcity of said materials.
Steel pistol bullet jackets are usually about as thick and as hard as a "tin" can. Barrel wear and accuracy are not considered important, because of the relatively small quantities fired in pistols and the purpose of the submachine guns that use them. 1951 stuff probably means French or Czech 9mm loaded in 8 round stripper clips.
